Lead Poisoning Most Likely Had Nothing To Do With The Fall Of The Roman Empire

The fall of the Roman Empire has historically been a topic of debate among historians. In the last decade, however, there has emerged a theory arguing that lead poisoning is what brought Rome to its knees. Newest findings, however, point the finger away from this causal relationship, according to Ars Technica.

The word plumbing originates from Rome, as they were using lead pipes for their extremely sophisticated water delivery system.(Latin: Plumbum; the element also has the sign Pb in the periodic table)

Historians and archaeologists later discovered that the Romans knew about the toxicity of lead in the human body and tried to mitigate it. They were certainly ingesting more of the toxic element than they would have if they had been drinking spring water. The concentrations in the water supply were up to 100 times more than what was found in spring water.

Lead is known to have no positive effect in the human body, and influences the immune system, brain development and function, and there are known cases of it inducing aggressive behavior. No wonder, then, that the historians would think that this toxic element was somehow at least partly responsible for the fall of the Empire which had standardized lead for use in water supplies all over the continent.

Now, a new study reveals that the city’s plumbing infrastructure was at its biggest and most complicated during the centuries leading up to the empire’s peak.

Working with a team, analysing content in 12-meter soil cores taken from Rome’s two harbors, Hugo Delile from France’s National Center for Scientific Research reached a conclusion. In a recent paper for Proceedings of the National Academy of Sciences, the researchers explain how water gushing through Rome’s pipes picked up lead particles.

Runoff from Rome’s plumbing system was dumped into the Tiber River, whose waters passed through both harbors. But the lead particles quickly sank in the less turbulent harbor waters, so Delile and his team hypothesized that deposited layers of the poisonous metal in the soil cores would correlate to a more extensive network of pipes used at the time.

In other words – more lead in a layer would mean more water flowing through lead pipes. Though this lead probably didn’t harm ocean wildlife, it did leave a clear signature behind.

Roman plumbing was a legendary achievement in civil engineering. Wealthy Romans had hot and cold running water, as well as a sewage system that whisked waste away. Then, about 2,200 years ago, the waterworks got an upgrade: the discovery of lead pipes (called fistulae in Latin) meant the entire system could be expanded dramatically.

Photo: Ancient Roman lead pipes of various sizes and lengths

The very existence of the pipe system was a sign of Rome’s fantastic wealth and power. Most lead in Rome came from distant colonies in today’s France, Germany, England, and Spain, which meant the Empire needed an extensive trade network to build out its water infrastructure. Plus, the cost of maintenance was huge. All pipes were recycled, but the city still had to repair underground leaks, check water source quality, and prevent the massive aqueducts from crumbling.

The city’s plumbing system, costing a fortune, was a good proxy for Rome’s fortunes. In their soil core from Ostia, Delile and his team even discovered evidence of the Roman Empire’s horrific civil wars during the first century BCE. As war sucked gold from the state’s coffers, there was no money to build new aqueducts nor to repair existing ones.

Around that time, the researchers saw a dramatic decrease in the amount of lead-contaminated water in the Ostia harbor—in fact, it drops about 50 percent from previous years:

[This] provides the first evidence of the scale of the contemporaneous reduction in flows in Rome’s lead pipe distribution system—of the order of 50%—resulting in decreased inputs of lead-contaminated water into the Tiber. [Augustus’]… progressive defeat of his rivals during the 30s BCE allowed his future son-in-law, Agrippa, to take control of Rome’s water supply by 33 BCE. Over the next 30 years, they repaired and extended the existing aqueduct and fistulae system, as well as built an unprecedented three new aqueducts, leading to renewed increase in [lead] pollution of the Tiber river.

Delile and the rest of the team saw a strong drop in lead after the mid-3rd century CE, when the researchers note “no more aqueducts were built, and maintenance was on a smaller scale.”

This corresponds to the apparent decline of lead and silver mining and of overall economic activity in the Roman Empire.